Carboxy-terminated polyesters

Linear polysiloxanes having reactive terminal groups are often condensed with reactive orgaiuc polymers. For example, hydroxy-terminated siloxanes can be condensed with a carboxy-terminated polyester, as illustrated in equation (28). The resulting polymers behave as thermoplastic elastomers, having some of the desirable properties of both siloxanes and polyesters. Similar condensation reactions have been used to synthesize siloxane copolymers with polyamides, polyethers, polycarbonates, and so on. 

Carboxy-terminated polyesters, based on isophtalic acid and aliphatic diols were synthesized, in a molecular weight range of M 1000-4000. They have the following schematic structures ... 

The synthesis of carboxy terminated polyesters in the molecular weight range of 1000-4000... 

The carboxy terminated polyesters become water dispensable only by neutralization with a base such as amines ... 

Table IV. Micellar Characteristics of Carboxy Terminated Polyesters Micelles Prepared by an Industrial Procedure...

Having shown that carboxy terminated polyesters present typical surfactant characteristics after neutralization with amines, it was of interest to examine their application possibilities in emulsion polymerization. Such polymerizations for styrene and for butyl-methacrylate (BMA) have been carried out either by a batch technique or by a semi- continuous procedure. The reaction conditions were the following ... 

Carboxy terminated polyesters, of diacid and tetracid type, have been synthesized and characterized by chain-end titration, by vapour pressure osmometry and by viscometry. 

Heterocyclic Epoxy Compounds. The technically most important heterocyclic epoxy resin is triglycidyl isocyanurate, obtained by reacting cyanuric acid with epichlorohydrin (Araldite PT 810, Ciba-Geigy Tepic, Nissan). This trifunctional epoxy resin is combined with carboxy-terminated polyesters to give weather-resistant powder coatings [2.122]-[2.124]. 

Polyester resins for powder coating are brittle solids with a relatively high Tg (50-60°C) and so the powder coating does not sinter during storage. Terephthalic acid (TPA) and NPG are used as the principal monomers with smaller amoimts of other monomers to increase fn and to reduce Tg to the desired level. Both hydroxy-and carboxy-terminated polyesters are used. The former are most commonly cross-linked with blocked isocyanates and the latter with epoxy resins. Other crosslinkers include 2-hydroxyalkylamides and tetramethoxymethylglycolmil. 

If the polyester synthesis is performed with equimolar amounts of diol and diacid, then, in addition to hydroxy, carboxy-terminated oligomers, dihydroxy- and dicarboxy-terminated oligomers are formed, as shown below. In a thermodynamic equilibrium, the molar ratios of the three functionality fractions should be 2 1 1, respectively. 

Carboxy-terminated oligomeric polyester compositions consisting of resorcinol, terephthalic isophthalic acid, diphenyl carbonate, and terephthalic acid catalyzed by titanium tetrabutoxide were prepared by Brunelle et al. (1) and used as thermosetting applications. 

PMR spectroscopy has been applied to the characterisation of a wide range of homopolymers including PMMA [286-289], PVC [290-294], PS [293, 295, 296], polyvinyl ethers [297-300], polyacrylic acid [301], poly(methyl-a-chloroacrylate) [302], carboxy terminated polybutadiene [303], poly(a-methyl styrene) [304], natural rubber [305-307], chlorinated polyisobutylenes [308], sulfonated PS resins [309, 310], polyvinyl phenyl ether [311], lactone polyester [312], chlorinated PVC [313], PC [314], poly 1,3 butadiene [315], poly-2-allyl phenyl acrylate [316], poly(4-methyl-pentene-1) [317], polymethacrylic acid [318], PP [296], cyclic ethers [319], polymethacrylonitrile [320], poly(a-methyl styrene) tetramer [321], PEG [322], PE [289], polyacrylamide [311], polymethylacrylamide [323], polypyrrolidone [324], polychloroprene [325], phenol formaldehyde resins [326, 327], Nylon 66 [328], polyvinylidene fluoride [329], polyvinyl formate [330], polyacrylonitrile [331], epoxy resins [332], allyl biguanide [333], poly(2-isopropyl-2-oxazollines) [334] and trehalose vinyl benzyl ether [335]. 

Writing the polymerisation reactions for the formation of Polyesters from (o-hydroxy acids and formation of carboxy terminated polybutadiene (CTPB) from butadiene in presence of an azo initiator, predict the number of carboxyl groups per molecular chain in each case. 

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